Conventional electroencephalography (EEG) systems have been employed to record brain waves in a patient by measuring intrinsic voltages or currents produced by the brain of the patient. Specifically, conventional EEG systems detect and amplify brain waves, and convert the brain waves into digital data to be compared with data associated with normal brain waves. These systems may be employed to detect possible spinal cord injuries, stroke, epilepsy and a variety of brain dysfunctions related to a psychology of a patient ranging from substance abuse to psychosis. For example, certain conventional EEG systems include a plurality of electrodes which can be positioned on the scalp of a patient. The electrodes are coupled to a switching system, which in turn is coupled to a preamplifier that is connected to an amplifier. The amplifier is connected to a sixteen (16) bit analog to 30 digital (A/D) converter, and the A/D converter is connected to a display. The A/D converter samples the EEG waves, and converts the EEG waves into the digital data to be shown on the display. However, such conventional system only may be adapted to obtain EEG recordings.
Conventional electrical impedance tomography (EIT) systems have been employed to produce electrical impedance images in medical applications. These EIT systems measure current or voltage distributions resulting from the currents being applied to a portion of the body of the patient, and generate an image of such portion of the body based on the measured current or voltage distributions. These conventional systems have been employed, e.g., to display changes in the thorax during breathing, the stomach during a gastric emptying, the heart during intraventricular hemorrhage, and the brain due to a physiological cerebral activity, and to monitor the progression of various lung diseases. For example, the conventional EIT system can be adapted to image changes in the brain due to a physiological cerebral activity may include a current generator coupled to a switching arrangement, such as a computer controlled multiplexor. A plurality of electrodes are positioned in contact with the patient's scalp, and are coupled to the switching arrangement. An amplifier is coupled to the electrodes, a sixteen (16) bit A/D converter is connected to the amplifier, and a computer is connected to the A/D converter.
In operation, the current generator applies current to the electrodes. For example, the current may be applied sequentially to the electrode pairs, or simultaneously to multiple pairs of electrodes, which is known as a parallel data collection. Moreover, potential differences between the electrode pairs may be measured to obtain analog signals, and these analog signals may be amplified by the amplifier. Subsequently, the A/D converter converts the analog signals to digital signals, and forwards the digital signals to the computer. In this manner, the data may be processed by the reconstruction software to obtain image changes in the brain due to a physiological cerebral activity, and provide these images on a display. However, such conventional system may be adapted to only obtain EIT recordings that are e.g., associated with the physiological cerebral activity, and may also be adapted to only monitor only certain organs. Moreover, such convention system only may obtain EIT recordings at a particular frequency.